FIGS. 47 show a conventional suspending rod, used for lifting up a massive body, for example, when power-generation facilities are set up. A suspending rod 10, elongated by screwing plural rods 10S to each other in the axis direction, is suspended from a beam portion, located at high elevations, of a steel structure to be used when a module of a boiler, associated with piping installation on the ground, is moved upward step by step in response to the associating stages on the ground and moved down as necessary. The rod 10S as a component of the suspending rod 10, which has a configuration continuously linked with plural top-shaped supported portions 12 in the axis direction, has a male screw part 14 at the end thereof and a female screw part 16 at the other end which engages with the male screw portion of another rod. Each rod of the suspending rod 10 is made to have the length of about 5 m in consideration of a storage space of rods, convenience or handling properties for transferring them between workplaces, workability in the lifting operations for the massive body, and so on. In the use of the suspending rod 10, the plural rods 10S are coupled by screwing each other in the axis direction, and the massive body is lifted up by a jack while being suspended at the lower portion of the suspending rod 10.
More specifically, as shown in FIG. 48, steel columns 22 are stood up around a heavy steel structure 20. A temporary beam 24 is horizontally mounted on the top of the steel column 22 to project from the top of the steel column 22. A center hole type jack 26 is placed on the temporary beam 24 and supports the suspending rod 10 attached with the heavy steel structure 20, such as a module of a boiler, at the lower portion thereof. The suspending rod 10 is structured by coupling the rods 10S shown in FIG. 47 so that the length of the suspending rod 10 corresponds to the height up to which the structure 20 is lifted. As shown in FIG. 49, the center hole type jack 26 lifts up the structure 20 by pushing up the suspending rod 10 with using the supporting part 12 formed in the rod 10.
The lifting steps are as follows. As shown in FIG. 49(1), the suspending rod 10, suspending the structure 20, is supported by an upper chuck 34, and the load of the structure 20 is received by the upper chuck 34, and a lower chuck 36 is released. In this state, a ram 32 is worked and pushes up the suspending rod 10 for a rod (one of the supported portions 12) so as to lift up the structure 20 through the suspending rod 10. The lower chuck 36 is closed when the suspending rod 10 is moved up for one rod, and the ram 32 is moved down so that the lower chuck 36 receives the lifting load (the suspending load) through the supporting part 12. When the lower chuck 36 supports the suspending rod 10, the upper chuck 34 is opened to move further down the ram 32. When the upper chuck 34 comes under the next supported portion, located beneath the supported portion supported previously by the upper chuck 34, the upper chuck 34 is closed again to support the suspending rod 10, and the lower chuck 36 is opened, and the above steps are repeated. When the coupling point of the rod 10 reaches above the center hole type jack 26, the lifting operations are intermitted in order to remove the top rod 10S.
Concerning the removing steps for the suspending rod 10, after the rod 10S to be removed is held firm by equipment, such as a crane, not to fall or overturn, the top rod 10S, coupled and screwed, is rotated in a direction to release the coupling manually with the use of a tool, such as a chain wrench, and then the top rod 10S is removed from its connecting rod 10S. The removed rod 10S is carried to a temporary storage place on the temporary beam 24, on which the center hole type jack 26 is placed, by a device, such as a crane, or alternatively, it is brought down on the ground for storing.
In the aforementioned method, the removed rod 10S should be moved down to the rod storage place positioned lower than the attaching/detaching position of the rods, or conversely, the rod 10S which is placed in the rod storage place should be moved up to the coupling position, therefore the rod 10S is not effortlessly transferred. Moreover, conventionally, the rod is transferred by hand, so that a large amount of manual efforts is required in addition to the possible occurrence of a rod being dropped.
The aforementioned lifting operations, using the hydraulic-actuated center hole type jack 26 and the suspending rod 10, are applied in a lifting operations for a large massive body, so that the coupling force between the rods 10 should be large and a large force is needed to rotate the suspending rod 10 in order to release the coupling. Additionally, the structure 20 must be lifted up while being horizontally balanced, so that plural center hole type jacks 26 are used simultaneously, and an operator takes charge of each center hole type jack 26, therefore workers are required in large numbers. Moreover, the operations are carried out on the temporary beam 24 at high elevations, so that there is a disadvantage of the safety of workers.
When the heavy steel structure 20 is lifted up and down by using plural jacks 26, the jacks 26 should be synchronously driven to lift up and down and the stroke displacement of the ram 32 of each jack 26 should be equalised so that the heavy steel structure 20 is not inclined. A controlling method for equalising strokes of plural jacks is proposed, in which a pressure regulating valve is provided in the returning side of a hydraulic jack and the stroke is equalised by adjusting the degree of opening of the valve (Japanese Patent Laid-open No. Hei7-315774). In the adjustment of the degree of opening of the pressure regulating valve, when any one of the jacks produces stroke, the feed of oil is stopped and the pressure regulating valves of the other jacks are adjusted in order so that each jack produces stroke.
In the controlling method for equalising strokes of the jacks as described in the above Patent Bulletin, the degrees of opening the pressure-adjusting valves of plural jacks are adjusted in order, so that when a number of jacks are used, it takes time to adjust the degree of opening of the valves, and additionally, a difference of the stroke displacement between the jacks easily occurs for reasons of a change of temperature in oil pressure during use, differences in time property of each device, and so on. Although the pressure regulating valves are adjusted in early stages, it is greatly difficult to equalise the strokes of the jacks. Therefore, the massive body is laboriously lifted up and down in parallel, so that a bending force acts on the suspending rod, and the valves must be adjusted again.
When the structure 20 is lifted, the plural center hole jacks 26 are synchronized to be worked uniformly in order that the structure 20 is lifted up not to incline, so that the removing operation for the suspending rod 10 should be carried out invariably after the actions of all center hole type jacks 26 are stopped. However, the number of cranes used for removing the rod 10S is limited, so that the plural rods 10S are sequentially removed in order by plural cranes, therefore the entire operating time period, including a time for lifting up the structure 20 and a time for removing the rods 10S, is longer and the working efficiencies are decreased. In addition, the safety of workers should be further considered for reasons of a drawn-out operation. In order to set the removed rod 10S on the temporary beam 24 or the ground, equipment, such as a crane, is required. The number of cranes or the like should be corresponded to the number of center hole type jacks 26. Therefore, as the number of equipment used is increased, the number of operators for the equipment is increased, resulting in expanding work schedules and complications for management.